What is the difference between a Table, View and Synonym in SQL?

A Table is a repository of data, where in the table itself is a physical entity. The table resides physically in the database.

A View is not a part of the database's physical representation. It is precompiled, so that data retrieval behaves faster, and also provide a secure accessibility mechanism.

See code example below:

Create table T_EMPLOYEE
(Emp_Id integer primary key,
Name varchar2(50)
Skillset varchar2(200),
Salary number(12,2),
DOB datetime);

Say there is a scenario where Salary is not to be shown to a group of users, a View may be created to display allowable information:

Create view EMP_SOME_DETAILS
as
(Select Emp_Id, Name, Skillset, DOB
From T_EMPLOYEE);

The advantages of using a view are as follows:
- It may access data from a table, multiple tables, view, multiple views, or a combination of these
- A view connects to the data of its base table(s).
- Provides a secure mechanism of data accessibility

Synonym is alternate name assigned to a table, view, sequence or program unit.
- It may be used to shadow the original name and owner of the actual entity
- Extends the reach of tables, by allowing public access to the synonym